1. Field of the Invention
This invention relates to a chemical analysis element cartridge for storing a plurality of chemical analysis elements such as those for quantitatively analyzing the content of a specific chemical component contained in a sample liquid such as blood or urine or those for quantitatively analyzing the activity of particular ionic substances contained in a sample liquid such as blood or urine.
2. Description of the Prior Art
There have been put into practice various "dry-to-the-touch" chemical analysis elements. For example, there has been proposed, for instance, in U.S. Pat. Nos. 3,992,158; 4,292,272 and 5,019,347 and European Patent 0 162 302B and put into practice a "dry-to-the-touch" chemical analysis film with which the content or the concentration of a specific chemical component contained in a sample liquid, the activity thereof or the content of a solid component can be quantitatively analyzed by only spotting a droplet of the sample liquid on the film. As such a dry chemical analysis film, there has been known an integrated multi-layered chemical analysis film (sometimes referred to as "multi-layered chemical analysis element") comprising a support sheet of organic polymer and a reagent layer formed on the support sheet. The reagent layer contains therein a reagent whose optical density changes by chemical reaction, biochemical reaction, immunoreaction or the like with a specific biochemical component contained in the sample liquid. A spreading layer is sometimes formed over the reagent layer. Further a dry chemical analysis film which is formed of filter paper and has one or more layers has been proposed, for instance, in U.S. Pat. No. 4,477,575, and partly put into practice.
The chemical analysis film is generally in the form of a film chip of a predetermined shape such as square or rectangle. In the past, the film chip is generally provided with a frame of organic polymer or the like for facilitating automated handling of the film chip. The film chip provided with such a frame is generally called a chemical analysis slide. However in a chemical analysis apparatus we have previously proposed, the chemical analysis film chip is used as it is without frame. The chemical analysis film without frame is generally referred to as "a frameless chemical analysis film".
Further there has been proposed, for instance, in U.S. Pat. Nos. 4,053,381 and 4,437,970 and put into practice a "dry-to-the-touch" electrolyte analysis slide for quantitatively analyzing the activity of particular ionic substances contained in a sample liquid such as blood or urine in a potentiometric way. The electrolyte analysis slide is a kind of electrochemical sensors and comprises a pair of ion-selective (or ion-specific) electrodes.
In this specification, the term "chemical analysis element" should be broadly interpreted to include the chemical analysis slide, the frameless chemical analysis film, the single-layered or multi-layered chemical analysis film formed of filter paper (with or without frame), and the electrolyte analysis slide described above.
For instance, in Japanese Utility Model Publication No. 57(1982)-53271 (U.S. Pat. No. 4,151,931), there is disclosed a chemical analysis element cartridge in which a plurality of the chemical analysis elements are stacked and from which the chemical analysis elements are taken out one by one. In the cartridge, a plurality of chemical analysis elements are stacked in a cartridge body which is provided with an element take-out port in a side surface of the upper portion thereof and the uppermost element is pushed out and fed to a chemical analysis apparatus through the element take-out port by a pusher blade which is moved in a horizontal direction. The stack of the elements are supported on a pressing member which is disposed in the cartridge body and is permitted to move only upward by a ratchet mechanism. The pressing member is lifted upward by a plunger inserted into the cartridge body from below so that the stack of the elements is moved upward by a distance equal to the thickness of one element and the second uppermost element is brought to the element take-out port each time the uppermost element is pushed out.
However this cartridge is disadvantageous in the following point. That is, when the cartridge falls or is subjected to an impact by accident during transfer or storing, an excessive pressure can act on the chemical analysis elements stored therein or the pressing member can be damaged, whereby take-out of the chemical analysis elements or measurement can be adversely affected. This problem is especially serious in the case of a cartridge storing therein chemical analysis elements such as electrolyte analysis slides which are relatively large in weight.
More particularly, in the aforesaid chemical analysis element cartridge where a pressing member having a ratchet mechanism is urged by a plunger, the ratchet mechanism permits the pressing member to be moved by a weak force in the direction of pushing the stack of the elements but does not permit the pressing member to be moved in the reverse direction. Accordingly when the cartridge falls with the element take-out port down, the stack of the elements is compressed toward the take-out port and the pressing member moves toward the take-out port and is locked there, whereby the stack of the elements is kept compressed and it can become impossible to take out the elements due to an excessively large pressure acting on the stack of the elements.
On the other hand when the cartridge falls with the end of the cartridge remote from the take-out port directed downward, the weight of the elements totally acts on the ratchet mechanism to damage the ratchet teeth and/or the ratchet claws, whereby it can become impossible to hold the uppermost element at the height of the take-out port, which gives rise to problem in taking out the element. For example assuming that the impact acting on the cartridge when it falls one meter is 1200G and the weight of fifty elements stored in the cartridge is 50 g, a force of 60 Kg acts on the pressing member. It is difficult for the ratchet claws to support such a large force.